JPH11230056A - Gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To elastically deform the expanded portion of a bush in the shrinking direction in diameter by forming a slit in the axial direction from an end section on a protruded portion side, and expanding the end section in diameter. SOLUTION: A wound bush 21 bent with a plate into a tubular shape is used as this bush. A gap 22 is formed as a slit between end faces facing each other when the plate is bent into the tubular shape. A tapered jig is inserted from one end of the wound bush 21 to expand one end in diameter. When first and second covers are fitted to a body with a side plate tightly inserted into a gear hole, the expanded portion 23 of the wound bush 21 is inserted into a through hole formed on the side plate. Even if the outer diameter R of the expanded portion 23 of the wound bush 21 is slightly larger than the diameter of the through hole, the expanded portion 23 is elastically deformed in the shrinking direction in diameter to absorb its error.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear pump for positioning a cover using a bush.

[0002]

2. Description of the Related Art Conventional gear pumps include, for example, those shown in FIGS. As shown in FIG. 4, a gear hole 2 is formed in the body 1, and a drive gear 3 and a driven gear 4 mesh with each other in the gear hole 2. Body 1
Has a first cover 5 attached to one end thereof. This first
A drive shaft hole 6 and a driven shaft hole 7 are formed in the cover 5, and bushes 8 and 9 are incorporated in the shaft holes 6 and 7. And these bush 8,
A shaft 3a of the drive gear 3 and a shaft 4a of the driven gear 4 are rotatably supported on an inner peripheral surface of the drive gear 3.

When the first cover 5 is attached to the body 1, a side plate 10 is fitted into the opening end of the gear hole 2. As shown in FIG.
0 has a drive shaft through hole 11 and a driven shaft through hole 12. The shaft 3a of the drive gear 3 and the shaft 4a of the driven gear 4 pass through the through holes 11 and 12, respectively.

A second cover 1 is attached to the other end of the body 1.
3 is installed. A drive shaft hole 14 and a driven shaft hole 15 are also formed in the second cover 13.
Bushs 16 and 17 are incorporated in these shaft holes 14 and 15. The inner peripheral surfaces of the bushes 16 and 17 rotatably support the shaft 3b of the drive gear 3 and the shaft 4b of the driven gear 4, respectively. The shaft 3b of the drive gear 3 projects outside from the second cover 13 and is connected to a drive source (not shown).

When attaching the second cover 13 to the body 1, the side plate 18 is fitted into the opening end of the gear hole 2. The side plate 18 has a drive shaft through hole 19 like the side plate 10.
And a driven shaft through-hole 20. The shaft 3b of the drive gear 3 and the shaft 4b of the driven gear 4 pass through these through holes 19 and 20, respectively.

The back surfaces of the side plates 10 and 18 are
Although not specifically shown, it is partitioned into a high-pressure area and a low-pressure area. Then, the pressure on the discharge side and the pressure on the suction side are led to each area. The side plates 10 and 18 thus configured are provided with gears 3 and 4 according to the pressure distribution.
Side to adjust the clearance between the gears 3 and 4 so as to eliminate leakage therefrom.

Here, the bushings 8, 9 assembled on the first cover 5 side and the bushings 16, 17 assembled on the second cover 13 side are made to protrude from the mounting surfaces of the first and second covers 5, 13, respectively. ing. When the first and second covers 5 and 13 are attached to the body 1, as shown in FIG. 6, the projecting portions of these bushes 8, 9, 16 and 17 are formed in side plates 10 and 18 respectively. 11, 12, 19, and 20.

In the gear pump described above, the side plates 10, 18 are incorporated in the gear holes 2 formed in the body 1, and the bush 8 is inserted into the through holes 11, 12, 19, 20 formed in the side plates 10, 18. , 9, 16,
The first and second covers 5,
13 is performed. Therefore, the first and second covers 5, 13 can be positioned with respect to the body 1 without using a separate member such as a positioning pin.

[0009]

However, in the prior art gear pump, the gear hole 2 and the side plates 10 and 18 are not provided.
Of course, but the side plates 10, 1
The dimensions of the through holes 11, 12, 19, 20 formed in 8 and the projecting portions of the bushes 8, 9, 16, 17 must be controlled very precisely. For example, bush 8, 9,
The diameters of the protruding portions of the through holes 11, 12, 1
If the diameter is smaller than the diameters 9 and 20, a gap is formed between them. As a result, the first and second covers 5 and 13 rattle with respect to the body 1 and cannot be positioned.

Conversely, if the diameter of the protruding portions of the bushes 8, 9, 16, 17 is larger than the diameter of the through holes 11, 12, 19, 20, the protruding portions are formed in the through holes 11, 12, 19,.
20 must be press-fitted, which makes it difficult to fit. Moreover, if the protruding portions of the bushes 8, 9, 16, 17 are press-fitted into the through holes 11, 12, 19, 20, the side plates 10, 18 are less likely to move. Therefore, the side plates 10, 18 and the gears 3, 4
Cannot be adjusted, resulting in increased leakage and poor pump performance. SUMMARY OF THE INVENTION An object of the present invention is to enable positioning of a cover with respect to a body while simplifying dimensional control, and to easily fit a projecting portion of a bush into a through hole formed in a side plate to prevent movement of the side plate. The aim is to provide a gear pump without any.

[0011]

Means for Solving the Problems The present invention comprises a body,
The gear hole formed in the body, the drive gear incorporated in the gear hole, the driven gear incorporated in the gear hole and engaged with the drive gear, the side plate fitted in the open end of the gear hole, and the drive gear formed in the side plate A drive shaft through hole through which the gear shaft penetrates, a driven shaft through hole through which the driven gear shaft penetrates, a cover attached to the end of the body that incorporates the side plate, and a cover A drive shaft including a formed drive shaft hole, a driven shaft hole formed in the cover, a tubular drive shaft bush incorporated in the drive shaft hole, and a cylindrical driven shaft bush incorporated in the driven shaft hole. Bush and driven shaft bush Is projected from the mounting surface of the cover, and when the cover is mounted on the body, each of the projecting portions of the bush is fitted into the drive shaft through hole and the driven shaft through hole formed in the side plate. It is assumed.

A first aspect of the present invention is that the bush for the drive shaft and the bush for the driven shaft are formed such that a slit is formed in the axial direction from the end on the protruding portion side, and the ends are enlarged in diameter. It has features. Second
The invention according to the first invention uses, as the bush, a wound bush obtained by bending a single plate into a cylindrical shape, and forming a gap between opposed end surfaces when the single plate is bent into a cylindrical shape. The feature is that the gap is formed as a slit.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a gear pump according to the present invention will be described with reference to FIGS. However, in this embodiment, only the bushes 8, 9, 16, 17 are changed, and the other configuration is exactly the same as the above-mentioned conventional example. Therefore, in the following, the differences will be mainly described, and the same components as those in the conventional example will be denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 1, as the bushes 8, 9, 16, 17, a wound bush 21 obtained by bending a single plate into a tubular shape is used. Then, a gap 22 is formed as a slit between the end faces facing each other when one sheet is bent into a cylindrical shape.

Further, from one end of the winding bush 21,
Although not specifically shown, a tapered jig is inserted,
This one end is enlarged in diameter. And, this enlarged diameter portion 23
Is made substantially the same as the diameter of the through holes 11, 12, 19, 20 formed in the side plates 10, 18.

It is desirable that the outer diameter R of the enlarged diameter portion 23 of the winding bush 21 and the diameter of the through holes 11, 12, 19, 20 are exactly the same. However, considering dimensional control, it is difficult to always keep exactly the same. In this case, in terms of the positioning of the first and second covers 5 and 13, the outer diameter R is set to the through holes 11, 12,
It must be larger than diameters 19 and 20. Therefore, dimensions are controlled so that the outer diameter R is not at least smaller than the diameters of the through holes 11, 12, 19, and 20.

The winding bush 21 thus constructed is firstly
The two covers 5 and 13 are assembled into the shaft holes 6, 7, 14 and 15 respectively. And these winding bush 21
Of the first and second covers 5,
13 protrudes from the mounting surface.

Now, the side plates 10 and 1 are
8 with the first and second covers 5,
When the 13 is attached to the body 1, the enlarged diameter portion 23 of the winding bush 21 is fitted into the through holes 11, 12, 19, 20 formed in the side plates 10, 18, respectively. At this time, as described above, the enlarged diameter portion 2 of the winding bush 21 is used.
3 is slightly larger than the diameters of the through holes 11, 12, 19, and 20, the expanded portion 23 is elastically deformed in the direction of reducing the diameter, thereby absorbing the error. Become.

In this case, the enlarged diameter portion 23 of the winding bush 21 is pressed into the through holes 11, 12, 19, and 20, but the enlarged diameter portion 23 of the winding bush 21 is elastically deformed in the direction of reducing the diameter. So that the side plates 10, 18
Can move against its elasticity. Therefore, if pressure is introduced to the back surfaces of the side plates 10 and 18, the side plates 10 and 18 move to the gears 3 and 4 and the gap between the gears 3 and 4 can be adjusted.

As shown in FIG. 3, for example, as shown in FIG. 3, one or a plurality of slits 24 may be formed in the axial direction of the bushing 8, 9, 16, 17 from the protruding end. May be formed. Further, in this embodiment, a three-part structure in which the first and second covers 5 and 13 are attached to the body 1 has been described. However, although not specifically shown, any one of the first and second covers 5 and 13 may be integrated into the body 1 and a two-part type may be attached to only one of the other. Absent.

[0020]

According to the first aspect of the present invention, the enlarged diameter portion of the bush can be elastically deformed in the direction of reducing the diameter. Therefore, even if the diameter of the enlarged portion of the bush is larger than the diameter of the through hole formed in the side plate, the error can be absorbed and easily fitted by elastically deforming the enlarged portion. . Further, if the pressure is guided to the back surface of the side plate, the side plate can move toward the gear side against its elasticity, and the gap between the side plate and the gear can be adjusted. In other words, if the diameter of the enlarged diameter portion of the bush is controlled so as not to be at least smaller than the diameter of the through hole formed in the side plate, the cover penetrates the projecting portion of the bush while positioning the cover with respect to the body. It is possible to provide a gear pump that is easily fitted into the hole and does not hinder the movement of the side plate.

According to the second aspect, in the first aspect, the slit can be formed only by bending a single plate into a cylindrical shape, so that almost no cost is required.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a winding bush 21 used for a gear pump according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which an enlarged diameter portion of a winding bush is fitted into a drive shaft through hole formed in a side plate;

FIG. 3 is a perspective view showing another example of a bush.

FIG. 4 is a perspective view showing a conventional gear pump.

FIG. 5 is a view showing the side plates 10 and 18;

6 is an enlarged view of a portion VI in FIG. 4, showing a state in which a protruding portion of a bush 8 is fitted into a drive shaft through hole 11 formed in a side plate 10. FIG.

[Explanation of symbols]

 1 Body 2 Gear Hole 3 Drive Gear 4 Driven Gear 3a, 3b Shaft 4a, 4b Shaft 5 First Cover 6, 14 Drive Shaft Hole 7, 15 Driven Shaft Hole 10, 18 Side Plate 11, 19 Drive Shaft Through Hole 12, 20 Driven Shaft through-hole 21 Winding bush 22 Gap 23 Large diameter portion 24 Slit

Claims (2)

[Claims] 1. A body, a gear hole formed in the body,
A drive gear built into the gear hole, a driven gear built into the gear hole and engaged with the drive gear, a side plate fitted into the open end of the gear hole, and a drive shaft formed on the side plate and through which the drive gear shaft passes A through hole, a driven shaft through hole formed in the side plate, through which the driven gear shaft penetrates, a cover attached to the end of the body on which the side plate is incorporated, a drive shaft hole formed in the cover, and a cover A driven shaft hole formed in the drive shaft, a cylindrical drive shaft bush incorporated in the drive shaft hole, and a cylindrical driven shaft bush incorporated in the driven shaft hole. , Cover mounting surface When the cover is attached to the body by projecting the bush and the driven shaft, each of the projecting portions of the bush is fitted into the drive shaft through hole and the driven shaft through hole formed in the side plate. A gear pump characterized in that the shaft bush has a slit formed in the axial direction from the end on the protruding portion side, and the end is enlarged in diameter. 2. A bush, wherein a wound bush obtained by bending a single plate into a cylindrical shape is used, and a gap is formed between opposing end faces when the single plate is bent into a cylindrical shape, and the gap is slit. The gear pump according to claim 1, wherein